AI Article Synopsis
- The study investigates the stability and migration pathways of large oxygen clusters in UO(2+x) using advanced simulations.
- It identifies that isolated cuboctahedral clusters can convert into more stable forms closely associated with the split quad-interstitial configuration.
- The research also analyzes differences between theoretical predictions and experimental data, indicating that the split quad-interstitial can migrate more efficiently than individual interstitials, albeit with some energetic barriers.
Article Abstract
Using ab initio molecular dynamics simulations and nudged elastic band calculations we examine the finite temperature stability, transition pathways, and migration mechanisms of large oxygen clusters in UO(2+x). Here we specifically consider the recently proposed split quad-interstitial and cuboctahedral oxygen clusters. It is shown that isolated cuboctahedral clusters may transform into more stable configurations that are closely linked to the split quad-interstitial. The split quad-interstitial is stable with respect to single interstitials occupying the empty octahedral holes of the UO(2) lattice. In order to better understand discrepancies between theory and experiments, the simulated atomic pair distribution functions for the split quad-interstitial structures are analyzed with respect to the distribution function for U(4)O(9) previously obtained from neutron diffraction data. Our nudged elastic band calculations suggest that the split quad-interstitial may migrate by translating one of its constituent di-interstitial clusters via a barrier that is lower than the corresponding barrier for individual interstitials, but higher than the barrier for the most stable di-interstitial cluster.
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| http://dx.doi.org/10.1063/1.4729842 | DOI Listing |
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